A mechanical watch typically includes a mainspring, a gear train, a balance wheel, an escapement, and an indicating dial. The mainspring stores mechanical energy for the watch. The gear train transfers the force of the mainspring to the balance wheel and measures the passage of time based upon the movement of the balance wheel. The balance wheel oscillates back and forth, with each swing taking the same amount of time to accurately measure time. The escapement mechanism keeps the balance wheel oscillating back and forth and, with each swing, allows the gear train to advance a set amount. The indicating dial, driven by the gear train, includes hands to display the measured time.
Mechanical watches may include additional functionalities, which are often referred to as complications. Exemplary complications include a chronograph/stopwatch, automatic winding, a power reserve indicator, an alarm, a calendar, etc. For example, a self-winding watch includes an eccentric weight, which rotates about a pivot point in response to movements of the user's wrist. This rotation is translated into the winding of the mainspring, e.g., via one or more gears and a pawl and ratchet arrangement.